The present invention relates generally to conductor filled elastomers and, more particularly, to a method of treating such elastomers to render selected regions thereof relatively nonconductive.
It is well known in the art to use conductive elastomer electrical connectors for interconnecting display panels to logic circuits in digital computers and wrist watches. Reference is made to U.S. Pat. No. 3,648,002 to DuRocher and U.S. Pat. No. 3,680,037 to Nellis which disclose conductive elastomer connectors in which conductive elastomer pads or contacts are mounted in openings in nonconductive elastomer retainers. The pads are formed of a resiliently compressible, electrically nonconductive elastomers having discrete, electrically conductive particles dispersed therethrough. The particles may be carbon black or metal, such as copper, nickel, or silver, or a combination of the same. The preferred elastomer is silicone rubber because of its long term stability and relatively low compression set. The conductive particles are responsive to compression of the pads to establish electrically conductive paths through the pads. U.S. Pat. No. 3,885,173 to Lee discloses a conductive elastomer connector in the form of a silicone rubber gasket having selected regions impregnated with silver.
In DuRocher, the nonconductive retainer is initially molded with openings therein, or molded as a solid disc and the openings are formed later. Thereafter, the openings are filled with silicone rubber having conductive particles dispersed therethrough which form the conductive pads or contacts of the connector. In the Nellis patent, the conductive elastomer contacts are precisely arranged in a mold and the voids therearound are filled with a flowable resin, such as silicone rubber, which forms the retainer for the contacts. While Lee does not disclose the method of forming his connector, presumably it is formed in the same manner as taught by Nellis.
It will be appreciated that in the prior art connector structures employing conductive elastomers as contacts, separate nonconductive retainers must be formed to receive the conductive contacts, or must be molded around the contacts. It is the purpose of the present invention to provide a method of treating selected regions of a conductive elastomer so as to render such regions relatively nonconductive, thus avoiding the requirement of making separate insulative retainers or substrates for discrete conductor filled elastomer contacts.